One type of conventional drawing device is designed to draw a warp thread into a hole of each heald by utilizing an air jet. For example, see Japanese Patent Application No. 63-128071 (1988) entitled Drawing Device, filed by the applicant of the present invention. In this device, a heald is disposed between a pair of adjacent thread drawing-in heads arranged in series, and a hole of the heald through which a thread is inserted is aligned with air jet passages that are formed in the heads. Thereafter, air is blown into the series of air jet passages from one end of the row of heads to blow a warp thread into the passages by means of the air stream, thereby drawing the thread into the hole of the heald.
Incidentally, there are two different types of heald, that is, the simplex type in which the hole is substantially on the center line that intersects the centers of guide holes which are provided at two ends of the heald, and the duplex type in which the hole is offset from the center line that intersects the centers of guide holes at two ends of the heald. When warp threads are to be drawn into healds of the latter type, the healds are supported by a guide rod with the direction of the healds being alternately changed so that the holes are alternately disposed on the two sides of the center line.
The above-described drawing device, which has been filed by the present applicant, is, however, adapted to draw warp threads into simplex healds and is therefore unsuitable for duplex healds in which the hole is offset from the center line.